Cyclic ethers are polymerized by various means to give products of widespread utility. For instance, ethylene oxide is polymerized to polyethylene oxide which is useful, in lower molecular weight grades, for ceramics (as a binder), cosmetics, lubricants, polyurethanes; and in higher molecular weight grades, for packaging film, denture adhesives, lubricants, flocculation and for other articles and products. Tetrahydrofuran (THF) is polymerized to poly(tetramethylene ether) glycol which is useful in the preparation of Spandex fibers; polyurethane resins which are useful in elastomeric parts; and thermoplastic elastomers which are useful for molding various mechanical parts. Therefore, improved methods of making these polymers are sought.
U.S. Pat. No. 3,842,019 describes the polymerization of oxiranes and other small ring compounds by a presumed cationic mechanism, using as the catalyst the decomposition products of metal perfluoroalkylsulfonates. These catalysts are described as "latent", that is no reaction occurs until the metal salt is decomposed. The reactions reported are relatively slow, even at elevated temperatures.
U.S. Pat. Nos. 5,084,586 and 5,124,417 describe the cationic polymerization of various monomers, including cyclic ethers, using onium cations, whose corresponding anions are fluororalkylsulfatometallates. Onium ion catalyzed cationic polymerizations are known, and there is no mention in these patents of the use of metal salts not containing onium ions, such as metal triflates, as catalysts for the polymerization of cyclic ethers.
J. S. Hrkach, et al., Macromolecules, vol. 23, p. 4042-4046 (1990) describe the polymerization of tetrahydrofuran using trimethylsilyl trifluoromethanesulfonate as the initiator. No mention is made of any other triflates as catalysts for this polymerization.
G. A. Olah, et al., J. Appl. Polym. Sci., Vol. 45, 1355-1360 (1992) describe the use of boron, aluminum and gallium tristriflate to catalyze the polymerization of THF.
S. L. Borkowsky, et al., Organometal., Vol. 10, p. 1268-1274 (1991) report that certain zirconium complexes can initiate the polymerization of tetrahydrofuran. No mention is made of zirconium perfluoroalkylsulfonates, or of copolymers.
I. Yamashita, et al., Kogyo Kagaku Zasshi, vol. 71, p. 1061-1064 (1968) describes the polymerization of tetrahydrofuran using a catalyst system consisting of a Lewis acid such as ferric chloride and a phosphorous compound such as triphenyl phosphite. The use of metal perfluoroalkylsulfonates is not mentioned.